The Observational Study Of The Magnetic Activity On Late-type Eclipsing Binaries

The solar activities such as sunspots,plages,flares and other phenomena are caused by the magnetic activity of the Sun.For the late-type stars with thick convective zones and rapid rotation,they also exhibit the similar magnetic activity phenomena.However,in many such kinds of stars,the details of the active phenomena caused by the magnetic fields are not understood well.In order to know the stellar magnetic activity better,we observe and study the magnetic activity of late-type eclipsing binaries by means of multi-color CCD photometry and high-resolution spectroscopy,and investigate the property and regularity of the detailed magnetic activity in the photosphere and chromosphere on late-type eclipsing binaries.In this Ph.D.thesis,we have made observational analysis for the photospheric starspot activity of eclipsing binary RT And and chromospheric activity of eclipsing binary SZ Psc.The results are obtained as follows:For active eclipsing binary RT And,we obtained three sets of multi-color light curves in 1999,2004 and 2005.For the light curves with full phase coverage in 2004,using the Wilson-Devinney synthesized light curve program,we derived the orbital parameters of the system and the starspot parameters simultaneously. The result indicates that the model with two spots on the primary is most successful in reproducing the observed light curve distortion of RT And.Although the light curves in 1999 and 2005 have not sufficient phase coverage,we still could use the starspot model to explain their light-curve variations successfully based on the photometric solution in 2004.By comparing the light curves of 1999,2004 and 2005,we found that the light curve distortion changes on both short and long time scales,especially the significant variation around the secondary minimum of light curves on a time scale of two months.Using the phase-dispersion minimization method,we analyzed the longitude of spots within the belt around longitude 270°,and the result suggests that the activity cycle of RT And may be 6.69±0.80 years.From 2004 to 2006,we made the high-resolution spectroscopic observations for the active eclipsing binary SZ Psc in five observing runs,and obtained many high-resolution echelle spectra including several optical chromospheric activity indicators(the He I D₃,Na I D₁,D₂,H_αand CaII IRT lines).Using the spectral subtraction technique,we studied the chromospheric activity of SZ Psc.All indicators show that the chromospheric activity of the system is associated with the cooler component.The ratio between the equivalent widths(EWs)of the excess emissions of the two CaII IRT indicators EW₈₅₄₂/EW₈₄₉₈is generally small,in range 1-3,which indicates optically thick emission in plage-like regions.From the 2006 data,an orbital phase modulation of the chromospheric emission maybe present.For the CaII 8542,8662 and H_αlines,it seems that the excess emission is stronger near the two quadratures of the system.However,for Na I D₁ line, it might be anti-correlated,which might be caused by the starspots.The absorption features are detected in the subtracted H_αlines,which probably result from prominence-like extended material seen on the stellar disk or mass-transfer between two components.Furthermore,we have established a simple model to simulate the effect of eclipse to the spectrum of eclipsing binary by considering the visible area of stellar disk,velocity shift,artificially rotationally broadening and limb-darkening. The consequence indicates that this model can reproduce the deformation of line profile of eclipsing binary well.Finally,we have made a prospect to the research topics of this field in future. Considering our present research status,a long-term project is proposed.